Field of Invention
The invention relates to a power management apparatus.
Related Art
FIG. 1A shows a conventional power management apparatus 1A, which cooperates with a power system P1 and a battery unit BAT. The power management apparatus 1A is connected with the battery unit BAT in parallel and includes a resistance R, a switch SW and a comparing circuit C.
The battery unit BAT is charged by the power provided by the power system P1. When detecting that the battery unit BAT achieves a predetermined voltage value, the comparing circuit C will turn on the switch SW, and therefore the current will flow through the resistance R so that the battery unit BAT can be protected from the overcharge situation.
FIG. 1B shows another conventional power management apparatus 1B, which cooperates with a power system P1 and a light emitting unit L. The power management apparatus 1B is connected to the light emitting unit L in parallel. The power management apparatus 1B is a Zener diode and the light emitting unit is a light emitting diode.
The light emitting unit L emits light according to the power provided by the power system P1. When the damage of the light emitting unit L leads to an open circuit and the voltage across the light emitting unit L exceeds the breakdown voltage of the power management apparatus 1B, the current is shunted to flow through the power management apparatus 1B so that the other light emitting unit L can still be assured of a normal operation.
The management scheme of the power management apparatus 1A is to consume extra charging power by the resistance R, and the power management apparatus 1B will also consume the power provided by the power system P1 when acting as a part of the flowing path of the power. In other words, the conventional power management apparatuses 1A and 1B will cause a large waste of the power, so they can't meet the present requirements of green environmental protection.
Therefore, it is an important subject to provide a power management apparatus that can effectively protect the controlled apparatus, avoid the waste of the power, and store and reuse the extra power.